从url获取文本内容

此方法适用于以.txt结尾的url

private StringBuilder readFromUrl(String url) throws IOException {
    InputStream is = new URL(url).openStream();
    try {
        BufferedReader rd = new BufferedReader(new InputStreamReader(is, Charset.forName("UTF-8")));
        StringBuilder sb = new StringBuilder();
        int cp;
        while ((cp = rd.read()) != -1) {
            sb.append((char) cp);
        }
        return sb;
    } finally {
        is.close();
    }
}